How to join on two columns using hibernate JPA annotations

I have the following three relationships

The

User

table

@OneToMany(mappedBy="user",fetch = FetchType.EAGER,cascade = CascadeType.ALL)
@SortNatural
SortedSet<Project> projects;

@OneToOne(cascade= CascadeType.ALL)
Company company;

The Project:

@ManyToOne
User user;
String company_name;

The Company:

@OneToOne(mappedBy = "company")
User user;
String name;

This gives me a

user_id

in the

Projects

table But I also want the company name , a cloumn from the company table to be in the projects table? How do I join user table and projects table on two columns (

user_id

and

company_id

) I want the

company_name

to be the name column from the Company table

Considering you are using a model like this:

One user has zero or one company;

One user has zero, one or more projects;

The project table holds a foreign key (user_id) to user;

The company table holds a foreign key (user_id) to user.

I think you can define the following JPA mappings:

//User table
@Id
Long id;
@OneToMany(mappedBy="user",fetch=FetchType.EAGER, cascade=CascadeType.ALL)
@SortNatural
SortedSet<Project> projects;

@OneToOne(mappedBy="user", fetch=FetchType.EAGER, cascade= CascadeType.ALL)
Company company;

//Project table
@Id
Long id;
@ManyToOne
@JoinColumn(name="user_id")
User user;

//Company table
@Id
Long id;
@OneToOne
@JoinColumn(name="user_id")
User user;
String name;

This way after retrieving a project p you can get the company’s name:

Project p = ... // code to select a project
String companyName = p.getUser().getCompany.getName();